Vitiligo is a chronic skin condition that causes loss of pigment, including melanin, resulting in irregular pale patches of skin. The precise etiology of vitiligo is complex and not fully understood although there is some evidence to suggest it is caused by a combination of auto-immune, genetic and environmental factors.
As many as 50% of people with vitiligo develop patches of de-pigmented skin appearing on extremities before their 20s. The patches may grow or remain constant in size and often occur symmetrically across both sides on the body. Occasionally small areas may repigment as they are “recolonised” by melanocytes and following melanin production and release. The location of vitiligo affected skin changes over time, with some patches re-pigmenting and others becoming affected. In some cases, mild trauma to an area of skin seems to cause new patches, for example, around the ankles (caused by friction with shoes or sneakers). Vitiligo may also be caused by stress factors that affect the immune system, causing the body to react or respond by “eliminating” or gradually loose the ability to produce and release melanin, skin pigment. Further, Vitiligo on the scalp may also affect the colour of the hair leaving white patches or streaks, with similar effects observed for facial and body hair.
There are a number of ways to alter the appearance of vitiligo without addressing its underlying cause. In mild cases, vitiligo patches can be hidden with makeup or other cosmetic solutions. If the affected person is pale-skinned, the patches can be made less visible by avoiding sunlight and the sun tanning of unaffected skin. However, exposure to sunlight may also cause the melanocytes to regenerate to allow the pigmentation to come back to its original colour.
Treatment options include medical treatments, surgical therapies, phototherapy and adjunctive treatments. Pharmaceuticals include topical steroid therapy, topical or oral psoralen phototherapy and depigmentation. Surgical therapies include skin grafts, melanocyte transplantations and micropigmentation or tattooing, while adjunctive therapies include sunscreens and cosmetics.
Despite the fact that many treatment options are available, each suffers from its own disadvantages and inherent limitations. For example, phototherapy involves exposing an individual to narrow band UV-B light (NB-UVB) resulting in skin repigmentation. Although phototherapy provides an effective short-term treatment option, repetitive exposure to NB-UVB light is needed to achieve continuous repigmentation. Further, while the frequency of exposure to NB-UVB light varies from individual to individual, repetitive exposure may result in unwanted side-effects including mild burning, blistering and skin irritations. Foremost, the repetitive treatment by UVB increases the risk of inducing skin malignancies, e.g. squamous cell carcinomas and basal cell carcinomas [Journal of Investigative Dermatology (2005) 124, 505-513; High Levels of Ultraviolet B Exposure Increase the Risk of Non-Melanoma Skin Cancer in Psoralen and Ultraviolet A-Treated Patients] [Mayo Clinics update].
Topical corticosteroid therapy has a reported success rate of up to 56%, however, long-term use of corticosteroids can result in thinning of the skin, stretch marks, and dilation of blood vessels. Further, treatment with oral or topical psoralen plus UVA (PUVA) has proven successful, however, patients need to ingest or apply psoralen before receiving the light treatment, and long term use of oral PUVA for the treatment of psoriasis has been associated with an increased incidence of skin cancer.
While immunomodulator creams are believed to cause repigmentation there is little or no scientific support to back this claim.
A need therefore exists to develop more effective treatments for vitiligo.